Adjustable gastric banding apparatus have provided an effective and substantially less invasive alternative to gastric bypass surgery and other conventional surgical weight loss procedures. Despite the positive outcomes of invasive weight loss procedures, such as gastric bypass surgery, it has been recognized that sustained weight loss can be achieved through a laparoscopically-placed gastric band, for example, the LAP-BAND® (Allergan, Inc., Irvine, Calif.) gastric band or the LAP-BAND AP® (Allergan, Inc., Irvine, Calif.) gastric band. Generally, gastric bands are placed about the cardia, or upper portion, of a patient's stomach forming a stoma that restricts the passage of food into a lower portion of the stomach. When the stoma is of an appropriate size that is restricted by a gastric band, food held in the upper portion of the stomach provides a feeling of satiety or fullness that discourages overeating. Unlike gastric bypass procedures, the gastric band apparatus are reversible and require no permanent modification to the gastrointestinal tract.
Over time, a stoma created by a gastric band may need adjustment in order to maintain an appropriate size, which is neither too restrictive nor too passive. Accordingly, prior art gastric band systems provide a subcutaneous fluid access port connected to an expandable or inflatable portion of the gastric band. By adding fluid to or removing fluid from the inflatable portion by means of a hypodermic needle inserted into the access port, the effective size of the gastric band can be adjusted to provide a tighter or looser constriction.
However, adjustment of the gastric band is conventionally performed by a syringe. The amount of fluid added by the syringe is often determined by a visual inspection of the syringe by the user. Such methods are often inaccurate since the user may not be able to determine accurately an amount of fluid injected into the gastric band through only a visual inspection of the syringe. Furthermore, the user may not know the precise pressure of the gastric band and thus may add too much or too little fluid to the gastric band. Detection of such pressure can be costly and time consuming since conventional pressure detection apparatuses will need to be sterilized after each use or disposed of after each use. Complete disposal of the pressure detection apparatus can be expensive and cost-prohibitive.
Some pressure detection apparatuses used in conjunction with syringes have also been disclosed, but these devices suffer from certain disadvantages. For example, Nolan, U.S. Pat. No. 5,808,203, generally discloses a pressure measuring device for a syringe, but Nolan integrates the pressure sensor as part of the syringe.
Reilly, U.S. Pat. No. 4,370,982, generally discloses an apparatus for measuring and detecting the pressure in a syringe being injected into a closed system. However, Reilly integrates the pressure sensor as part of the syringe.
Dlugos et al., U.S. Pat. Pub. No. 2008/0015406 generally discloses an external pressure sensing system. Dlugos discloses that a pressure sensing portion comprises a reusable sensor portion and a disposable cap portion. The reusable sensor portion and the disposable cap portion are configured to selectively engage one another. When coupled with the reusable sensor portion, the disposable cap portion is in fluid communication with the reusable sensor portion, such that pressure of fluid within tubing may be communicated to the reusable sensor portion via the disposable cap portion. In one embodiment, the disposable cap portion comprises the pressure dome described in Adolfs et al., U.S. Pat. No. 6,725,726. The reusable sensor portion comprises a pressure port, which is configured to receive such fluid pressure communications from the disposable cap portion. For instance, the pressure port may comprise a diaphragm or other structure suited for receiving fluid pressure communications. The reusable sensor portion further comprises a pressure sensor, such as a transducer, which is configured to provide pressure data via a cable to an interface component. The interface component is operable to process such pressure data and communicate it to a display device via a cable. However, Dlugos suffers from the drawback that it does not disclose the use of a disposable membrane, that the diaphragm is a reusable membrane, or that the diaphragm in the reusable sensor portion should contact a diaphragm in the disposable cap portion. This can, for example, result in inaccurate pressure information and/or contamination of the fluid being injected into the gastric band.
Thus, there is a need for a method and system for determining pressure in a syringe, and more specifically to a syringe pressure accessory which can be connected to a syringe to determine pressure in a syringe, an access port, a catheter, and a gastric band.